Wide-angle imaging lens having lenses of −++−+ refractive powers

ABSTRACT

A wide-angle imaging lens including a first lens element, a second lens element, an aperture, a third lens element, a fourth lens element and a fifth lens element arranged in sequence from an object side to an image side along an optical axis is provided. The refractive powers of the first to the fifth lens elements are negative, positive, positive, and negative.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan applicationserial no. 107130462, filed on Aug. 31, 2018. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of this specification.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an optical imaging lens, and inparticular, to a wide-angle imaging lens.

2. Description of Related Art

In recent years, popularization of mobile phones and digital cameras hasbrought explosion of photographic modules, and for the wide-angleimaging lenses that capture images and videos, it is hoped that thedesign will be lightweight and short. However, at this stage of thewide-angle imaging lens usually has a total track length (TTL), and thusis unfavourable for thinning of a lens. In view of the problem, how todesign an imaging lens with high imaging quality, a relatively small TTLand a wide visual angle is always the direction of efforts of thoseskilled in the art.

SUMMARY OF THE INVENTION

The present invention provides a wide-angle imaging lens with a widevisual angle, a short lens length and a good optical quality.

An embodiment of the invention presents a wide-angle imaging lensincluding a first lens element, a second lens element, an aperture, athird lens element, a fourth lens element and a fifth lens arranged in asequence from an object side to an image side along an optical axis isprovided. Each of the first lens element to the fifth lens elementincludes an object-side surface acing the object side and allowingimaging rays to pass through and an image-side surface facing the imageside and allowing imaging rays to pass through, and the lens elementswith refractive power are only the five abovementioned lens elements.The first lens element has negative refractive power. An object-sidesurface of the first lens element includes a concave surface in thevicinity of the optical axis, and an image-side surface of the firstlens element is a concave surface. The second lens element has positiverefractive power. An object-side surface of the second lens element is aconvex surface. The third lens element has positive refractive power. Anobject-side surface of the third lens element is a convex surface. Animage-side surface of the third lens element is a convex surface. Thefourth lens element has negative refractive power. An object-sidesurface of the fourth lens element is a concave surface. An image-sidesurface of the fourth lens element includes a concave portion in thevicinity of the optical axis. The fifth lens element has positiverefractive power, and an image-side surface of the fifth lens element isa convex surface.

In an embodiment of the present invention, the wide-angle imaging lensdescribed above satisfies: −0.8≤EFL/R1<0, where the EFL is an effectivefocal length of the wide-angle imaging lens, and the R1 is the radius ofcurvature on the object-side surface of the first lens element.

In an embodiment of the present invention, the wide-angle imaging lensdescribed above satisfies: 0.8≤|EFL/f1|≤1.2, where the EFL is aneffective focal length of the wide-angle imaging lens, f1 is a focallength of the first lens element, and |EFL/f1| is an absolute value ofEFL/f1.

In an embodiment of the present invention, the wide-angle imaging lensdescribed above satisfies: −3.0≤(R3+R4)/(R3−R4)≤0.9, where R3 is acurvature radius of the object-side surface of the second lens element,and R4 is a curvature radius of the image-side surface of the secondlens element.

In an embodiment of the present invention, a field angle of the wideangle imaging lens ranges from 130 degrees to 150 degrees.

In an embodiment of the present invention, in a first lens element, asecond lens element, a third lens element, a fourth lens element and afifth lens element with refractive power, the refractive index of thesecond lens element is greater than the refractive index of the otherlens elements with refractive power, and the Abbe number of the secondlens element is less than the Abbe number equals to other lens elementswith refractive power.

In an embodiment of the present invention, an object-side surface of thefirst lens element is a concave surface, and includes a concave portionin the vicinity of a periphery. An object-side surface of the secondlens element is a convex surface. The image-side surface of the firstlens element includes a convex portion located in the vicinity of theoptical axis and a concave portion located in the vicinity of aperiphery. An object-side surface of the fifth lens element includes aconvex portion in the vicinity of the optical axis and a concave portionin the vicinity of a periphery.

In an embodiment of the present invention, an object-surface of thefirst lens element includes a convex portion in the vicinity of aperiphery. An object-side surface of the second lens element is a convexsurface. An image-side surface of the fourth lens element includes aconcave portion in the vicinity of the optical axis and a convex portionin the vicinity of a periphery. An object-side surface of the fifth lenselement includes a convex portion in the vicinity of the optical axisand a concave portion in the vicinity of a periphery.

In an embodiment of the present invention, an object-side surface of thefirst lens element is a concave surface, and includes a concave portionin the vicinity of a periphery. An object-side surface of the secondlens element is a convex surface. An object-side surface of the fourthlens element is a concave surface, and includes a concave portion in thevicinity of a periphery. An image-side surface of the fifth lens elementis a convex surface.

In an embodiment of the present invention, an object-side surface of thefirst lens element is a concave surface, and includes a concave portionin the vicinity of a periphery. An object-side surface of the secondlens element is a concave surface. An image-side surface of the fourthlens element includes a concave portion in the vicinity of the opticalaxis and a convex portion in the vicinity of a periphery. An image-sidesurface of the fifth lens element is a concave surface.

Based on the above, the beneficial effect of the wide-angle imaging lensof the embodiments of the present invention is: by concave and convexshape design and arrangement of the object-side surfaces or image-sidesurfaces of the lens elements and combination of the refractive power ofthe lens elements, the wide-angle imaging lens can achieve a wide visualangle effect, a shorter lens length, and have good imaging quality.

In order to make the aforementioned features and advantages of thepresent invention comprehensible, embodiments accompanied withaccompanying drawings are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a wide-angle imaging lens according toa first embodiment of the present invention.

FIG. 2A to FIG. 2D are diagrams of a longitudinal spherical aberrationand each aberration according to the first embodiment.

FIG. 3 is a schematic diagram of a wide-angle imaging lens according toa second embodiment of the present invention.

FIG. 4A to FIG. 4D are diagrams of a longitudinal spherical aberrationand each aberration according to the second embodiment.

FIG. 5 is a schematic diagram of a wide-angle imaging lens according toa third embodiment of the present invention.

FIG. 6A to FIG. 6D are diagrams of a longitudinal spherical aberrationand each aberration according to the third embodiment.

FIG. 7 is a schematic diagram of a wide-angle imaging lens according toa fourth embodiment of the present invention.

FIG. 8A to FIG. 8D are diagrams of a longitudinal spherical aberrationand each aberration according to the fourth embodiment.

DESCRIPTION OF THE EMBODIMENTS

In the present specification, that a lens element has positiverefractive power (or negative refractive power) refers to that therefractive power, calculated based on the theory of Gaussian optics, ofthe lens element on an optical axis is positive (or negative). In animaging lens set, each lens element is radially symmetric with theoptical axis as a symmetry axis. Each lens element includes anobject-side surface and an image-side surface opposite to theobject-side surface. The object-side surface and the image-side surfaceare defined as surfaces through which imaging rays pass. Herein, theimaging ray includes a chief ray and a marginal ray. The object-sidesurface (or the image-side surface) includes a portion in a vicinity ofthe optical axis and a portion in a vicinity of a periphery of the lenselement surrounding and connecting the portion in a vicinity of theoptical axis. The portion in a vicinity of the optical axis is a portionthrough which the imaging rays pass on the optical axis. The portion ina vicinity of a periphery is a portion which the marginal rays passthrough.

That a surface (object-side surface or image-side surface) of the lenselement is a convex surface or concave surface in the vicinity of theoptical axis (or the portion in a vicinity of a periphery) may bedetermined by that an intersection of a ray (or a ray extending line)passing through the region in parallel and the optical axis is on animage side or an object side (ray focus determination method). Forexample, after the ray passes through the region and if the ray isfocused towards the image side and the intersection with the opticalaxis may be on the image side, the region is a convex portion. On thecontrary, after the ray passes through the region and if the raydiverged, the intersection of the extending line thereof and the opticalaxis is on the object side. A surface shape of the surface in thevicinity of the optical axis may be judged according to a judgmentmanner adopted by those skilled in the art, that is, the surface isjudged to be concave or convex according to a positive or negative valueof R (a paraxial curvature radius). For the object-side surface, whenthe value of R is positive, it is determined that the object-sidesurface is a convex surface in the vicinity of the optical axis, thatis, the object-side surface includes a convex portion in the vicinity ofthe optical axis; and when the value of R is negative, it is determinedthat the object-side surface is a concave surface in the vicinity of theoptical axis, that is, the object-side surface includes a concaveportion in the vicinity of the optical axis. For the image-side surface,when the value of R is positive, it is determined that the image-sidesurface is a concave surface in the vicinity of the optical axis, thatis, the image-side surface includes a concave portion in the vicinity ofthe optical axis; and when the value of R is negative, it is determinedthat the image-side surface is a convex surface in the vicinity of theoptical axis, that is, the image-side surface includes a convex portionin the vicinity of the optical axis.

A surface (object-side surface or image-side surface) of the lenselement may include one or more convex portions, one or more concaveportions or a combination of the two. When the surface includes theconvex portion and the concave portion, the surface includes aninflection point. The inflection point is a turning point between theconvex portion and the concave portion. That is, the surface turns fromconvex to concave or turns from concave to convex at the inflectionpoint. On the other aspect, when the surface only includes the convexportion or the concave portion, the surface includes no inflectionpoint.

Referring to FIG. 1, a wide-angle imaging lens 10 according to a firstembodiment of the present invention sequentially includes a first lenselement 1, a second lens element 2, an aperture 0, a third lens element3, a fourth lens element 4, a fifth lens element 5 and an optical filter9 from an object side to an image side along an optical axis I. Theobject side is the side facing an object to be photographed, and theimage side is the side facing an image plane 100. Rays emitted by theobject to be photographed, after entering the wide-angle imaging lens10, may sequentially pass through the first lens element 1, the secondlens element 2, the aperture 0, the third lens element 3, the fourthlens element 4, the fifth lens element 5 and the optical filter 9 andthen form an image on the image plane 100. The optical filter 9 is, forexample, an infrared ray (IR) cut filter, and is configured to preventaffecting imaging quality caused by transmission of an infrared ray ofpartial wave band in the ray to the image plane 100. However, thepresent invention is not limited thereto.

The first lens element 1, the second lens element 2, the third lenselement 3, the fourth lens element 4, the fifth lens element 5 and theoptical filter 9 include object-side surfaces 11, 21, 31, 41, 51 and 91facing the object side and allowing imaging rays to pass through andimage-side surfaces 12, 22, 32, 42, 52 and 92 facing the image side andallowing imaging rays to pass through respectively.

The first lens element 1 has negative refractive power. The object-sidesurface 11 of the first lens element 1 is a concave surface, andincludes a concave portion 112 located in the vicinity of the opticalaxis I and a concave portion 114 located in the vicinity of a periphery.The image-side surface 12 of the first lens element 1 is a concavesurface, and includes a concave portion 122 located in the vicinity ofthe optical axis I and a concave portion 124 located in the vicinity ofa periphery.

The second lens element 2 has positive refractive power. The object-sidesurface 21 of the second lens element 2 is a convex surface, andincludes a convex portion 211 located in the vicinity of the opticalaxis I and a convex portion 213 located in the vicinity of a periphery.The image-side surface 22 of the second lens element 2 is a convexsurface, and includes a convex portion 221 located in the vicinity ofthe optical axis I and a convex portion 223 located in the vicinity of aperiphery.

An aperture 0 is arranged between the second lens element 2 and thethird lens element 3.

The third lens element 3 has positive refractive power. The object-sidesurface 31 of the third lens element 3 is a convex surface, and includesa convex portion 311 located in the vicinity of the optical axis I and aconvex portion 313 located in the vicinity of a periphery. Theimage-side surface 32 of the third lens element 3 is a convex surface,and includes a convex portion 321 located in the vicinity of the opticalaxis I and a convex portion 323 located in the vicinity of a periphery.

The fourth lens element 4 has negative refractive power. The object-sidesurface 41 of the fourth lens element 4 is a concave surface, andincludes a concave portion 412 located in the vicinity of the opticalaxis and a concave portion 414 located in the vicinity of a periphery.The image-side surface 42 of the fourth lens element 4 includes aconcave portion 422 located in the vicinity of the optical axis I and aconvex portion 423 located in the vicinity of a periphery.

The fifth lens element 5 has positive refractive power. The object-sidesurface 51 of the fifth lens 5 includes a convex portion 511 in thevicinity of the optical axis I and a concave portion 514 in the vicinityof a periphery. The image-side surface 52 of the fifth lens element 5 isa convex surface and includes a convex portion 521 in the vicinity ofthe optical axis I and a convex portion 523 in the vicinity of aperiphery.

In the wide-angle imaging lens 10 according to the present embodiment,the lens elements with refractive power are only the five abovementionedlens elements. Moreover, in the present embodiment, the first lenselement 1 to the fifth lens element 5 may be made from, but not limitedto, a plastic material, so as to meet a lightweight requirement. Inanother embodiment, the first lens element 1 to the fifth lens element 5may be made from a glass material. In another example, at least one ofthe first lens element 1 to the fifth lens element 5 may be made fromthe glass material, while the other lens elements are made from theplastic material.

Other detailed optical data in the first embodiment is shown in Table 1.In table 1, A spacing (mm) corresponding to the object-side surface 11of the first lens element 1 is 0.200 and represents that a distance(i.e., a thickness of the first lens element 1 on the optical axis I)between the object-side surface 11 of the first lens element 1 and theimage-side surface 12 of the first lens element 1 on the optical axis Iis 0.200 mm. A spacing (mm) corresponding to the image-side surface 12of the first lens element 1 is 0.193 and represents that a distancebetween the image-side surface 12 of the first lens element 1 and theobject-side surface 21 of the second lens element 2 is 0.193 mm. Otherfields about the spacing (mm) may be reasoned in the same manner andwill not be repeated below.

TABLE 1 First embodiment Curvature Name of the radius Spacing RefractiveAbbe Focal length element Surface (mm) (mm) index number (mm) ObjectInfinite Infinite First lens Object-side −5.413 0.200 1.545 55.9 −0.4536element 1 surface 11 Image-side 0.263 0.193 surface 12 Second lensObject-side 1.044 0.525 1.651 21.5 1.486 element 2 surface 21 Image-side−10.445 0.050 surface 22 Aperture 0 Infinite 0.050 Third lensObject-side 0.487 0.226 1.545 55.9 0.4837 element 3 surface 31Image-side −0.481 0.05. surface 32 Fourth lens Object-side −1.026 0.2001.651 21.5 −0.6331 element 4 surface 41 Image-side 0.742 0.102 surface42 Fifth lens Object-side 1.03. 0.233 1.545 55.9 0.7367 element 5surface 51 Image-side −0.606 0.100 surface 52 Filter 9 Object-sideInfinite 0.150 1.516 64.1 Surface 91 Image-side Infinite 0.249 surface92 Image plane Infinite 100

In the present embodiment, the object-side surfaces 11, 21, 31, 41 and51 and the image-side surfaces 12, 22, 32, 42 and 52, totally 10surfaces, of the first lens element 1, the second lens element 2, thethird lens element 3, the fourth lens element 4 and the fifth lenselement 5 are all aspherical surfaces, and these aspherical surfaces aredefined according to Formula (1):

$\begin{matrix}{{Z(Y)} = {{\frac{Y^{2}}{R}\text{/}\left( {1 + \sqrt{1 - {\left( {1 + K} \right)\frac{Y^{2}}{R^{2}}}}} \right)} + {\sum\limits_{i = 1}^{n}\;{A_{i} \times Y^{i}}}}} & (1)\end{matrix}$

In Formula (1), Y is distance between a point on an aspherical curve andthe optical axis I. Z is depth of the aspherical surface. R is curvatureradius at a position, near the optical axis I, of the surface of thelens element. K is conic constant. A_(i) is ith-order asphericalcoefficient.

Each aspherical coefficient of the object-side surface 11 of the firstlens element 1 to the image-side surface 52 of the fifth lens element 5in Formula (1) is shown in Table 2. Field number 11 in Table 2represents the aspherical coefficients of the object-side surface 11 ofthe first lens element 1, and the other fields may be reasoned in thesame manner.

TABLE 2 Surface K A₄ A₆ A₈ 11 −1.0368E+01  0.0000E+00 0.0000E+00 0.0000E+00 12 −1.4762E+00  0.0000E+00 0.0000E+00  0.0000E+00 21−1.2380E+00 −1.9191E+00 3.9464E+00  0.0000E+00 22 −9.7840E+01 2.6251E+00 −2.9890E+01   3.6413E+03 31  1.1854E+00  9.2423E−01−1.1588E+02   7.1875E+03 32  3.3551E+00 −1.5233E+01 4.5599E+02−6.7467E+03 41 −3.9546E+00 −3.8215E+01 5.0400E+02 −4.1404E+03 42−3.2674E+01 −1.2981E+01 1.3391E+02 −3.2228E+01 51  6.6145E+00−3.5008E+00 −1.7801E+01  −2.2627E+01 52 −1.5460E+00  5.9154E+001.5793E+01 −7.1609E+02 Surface A₁₀ A₁₂ A₁₄ A₁₆ 11 0.0000E+00 0.0000E+000.0000E+00 0.0000E+00 12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 210.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 22 −6.3245E+04  0.0000E+000.0000E+00 0.0000E+00 31 −2.4305E+05  2.7701E+06 0.0000E+00 0.0000E+0032 6.2146E+04 1.9606E+05 0.0000E+00 0.0000E+00 41 −5.7346E+04 6.8114E+05 0.0000E+00 0.0000E+00 42 −8.5608E+03  5.5614E+04 0.0000E+000.0000E+00 51 3.0995E+03 −3.2514E+04  7.5712E+04 0.0000E+00 525.4886E+03 −2.0078E+04  2.8502E+04 0.0000E+00

A relationship among important parameters in the wide-angle imaging lens10 according to the first embodiment is shown in Table 3.

TABLE 3 EFL 0.40 mm Half Angle of View (HFOV) 71.0 degrees TTL 2.328 mmf-number 5.00 EFL/R1 −0.08 |EFL/f1| 0.88 (R3 + R4)/(R3 − R4) −0.82

The EFL of the wide-angle imaging lens 10 according to the firstembodiment is 0.40 mm. The HFOV is 71.0 degrees. The TTL is a distancebetween the object-side surface 11 of the first lens element 1 and theimage plane 100 on the optical axis I, and is 2.328 mm. The f-number is5.00. EFL/R1 is −0.08, where R1 is the curvature radius of theobject-side surface 11 of the first lens element 1. |EFL/f1| is 0.88,where f1 is the focal length of the first lens element 1.(R3+R4)/(R3−R4) is −0.82, where R3 is the curvature radius of theobject-side surface 21 of the second lens element 2, R4 is the curvatureradius of the image-side surface 22 of the second lens element 2.

Referring to FIG. 2A to FIG. 2D, FIG. 2A graphically illustrateslongitudinal spherical aberrations on the image plane 100 in case ofwavelengths of 656 nanometers, 587 nanometers and 486 nanometersaccording to the first embodiment. FIG. 2B and FIG. 2C graphicallyillustrate a field curvature aberration in a sagittal direction and afield curvature aberration in a tangential direction on the image plane100 in case of the wavelength of 587 nanometers according to the firstembodiment respectively. FIG. 2D graphically illustrates a distortionaberration on the image plane 100 in case of the wavelength of 587nanometers according to the first embodiment.

Referring to FIG. 2A again, curves of each wavelength are quite close toeach other and get close to the middle, indicating that off-axis rays ofeach wavelength at different heights are focused nearby an imagingpoint. From deflection amplitudes of the curves of each wavelength, itcan be seen that imaging point deviations of the off-axis rays atdifferent heights are controlled to be within a range of ±0.01 mm.Therefore, the spherical aberration of the same wavelength is actuallyobviously improved in the first embodiment. In addition, distances amongthe three representative wavelengths are also quite close, indicatingthat imaging positions of the rays of different wavelengths have beenquite concentrated, so that chromatic aberrations are also obviouslyimproved.

In the two field curvature aberration diagrams of FIG. 2B and FIG. 2C, afocal length variation of the representative wavelength 587 nanometersin the whole field of view falls within the range of ±0.01 mm,indicating that aberrations may be effectively eliminated in the firstembodiment. The distortion aberration diagram of FIG. 2D shows that thedistortion aberration in the first embodiment is kept within a range of±50%, indicating that the distortion aberration in the first embodimenthas met a requirement on imaging quality of an optical system. Thus, itcan be seen that high imaging quality may still be achieved in the firstembodiment, compared with an existing optical lens, even under thecondition that the TTL of the lens has been reduced to approximately2.328 mm.

FIG. 3 is a schematic diagram of a wide-angle imaging lens according toa second embodiment of the present invention. FIG. 4A to FIG. 4D arediagrams of a longitudinal spherical aberration and each aberrationaccording to the second embodiment. Referring to FIG. 3 at first, thesecond embodiment of the wide-angle imaging lens 10 of the presentinvention is substantially similar to the first embodiment, and thedifference therebetween is as follows: each optical data, asphericalcoefficient and parameter between these lens elements 1, 2, 3, 4 and 5are more or less different. In addition, the object-side surface 11 ofthe first lens element 1 includes a concave portion 112 in the vicinityof the optical axis I and a convex portion 113 in the vicinity of aperiphery. It should be noted that, for clearly presenting the diagram,it should be mentioned that the same reference numbers of the concaveportions and the convex portions in the two embodiments are omitted inFIG. 3.

The other detailed optical data in the second embodiment is shown inTable 4. Each aspherical coefficient of the object-side surface 11 ofthe first lens element 1 to the image-side surface 52 of the fifth lenselement 5 in the second embodiment in Formula (1) is shown in Table 5.

TABLE 4 Second embodiment Curvature Name of the radius SpacingRefractive Abbe Focal length element Surface (mm) (mm) index number (mm)Object Infinite Infinite First lens Object-side −0.533 0.220 1.545 55.9−0.4696 element 1 surface 11 Image-side 0.564 0.159 surface 12 Secondlens Object-side 9.809 0.435 1.651 21.5 1.8147 element 2 surface 21Image-side −1.319 0.050 surface 22 Aperture 0 Infinite 0.065 Third lensObject-side 0.715 0.317 1.545 55.9 0.5899 element 3 surface 31Image-side −0.478 0.050 surface 32 Fourth lens Object-side −0.672 0.2201.651 21.5 −0.4592 element 4 surface 41 Image-side 0.608 0.050 surface42 Fifth lens Object-side 0.492 0.485 1.545 55.9 0.5587 element 5surface 51 Image-side −0.522 0.100 surface 52 Filter 9 Object-sideInfinite 0.150 1.516 64.1 Surface 91 Image-side Infinite 0.350 surface92 Image plane Infinite 100

TABLE 5 Surface K A₄ A₆ A₈ 11 −1.6947E+01  1.2823E+00 −3.3119E+003.1385E+00 12  2.4432E+00  4.8012E−01  2.9574E+01 0.0000E+00 21 5.6530E+01 −4.3623E+00  8.1300E+01 −4.9949E+02  22 −2.3080E+01−3.7925E+00  9.0788E+01 −6.2050E+03  31  4.1783E+00 −3.7100E+00−2.1961E+02 7.2770E+03 32 −3.6667E+00 −3.0030E+00 −6.1651E+02 8.6998E+0341  6.3321E+00 −1.1510E+00 −3.7726E+02 4.7780E+02 42 −3.0926E+01 2.1012E+00 −1.9495E+02 2.9850E+03 51  8.8206E−02 −5.6890E+00 2.1178E+00 −2.1988E+02  52 −1.1123E+01 −6.7840E−01  4.7378E+01−6.7124E+02  Surface A₁₀ A₁₂ A₁₄ A₁₆ 11 0.0000E+00 0.0000E+00 0.0000E+000.0000E+00 12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 21 0.0000E+000.0000E+00 0.0000E+00 0.0000E+00 22 1.3689E+05 0.0000E+00 0.0000E+000.0000E+00 31 −1.7019E+05  2.7701E+06 0.0000E+00 0.0000E+00 32−4.0065E+04  1.9606E+05 0.0000E+00 0.0000E+00 41 2.4774E+04 6.8114E+050.0000E+00 0.0000E+00 42 −2.0934E+04  5.5614E+04 0.0000E+00 0.0000E+0051 4.8334E+03 −3.3808E+04  7.5794E+04 0.0000E+00 52 4.3153E+03−1.3462E+04  1.6636E+04 0.0000E+00

A relationship among important parameters in the wide-angle imaging lens10 according to the second embodiment is shown in Table 6.

TABLE 6 EFL 0.38 mm Half Angle of View (HFOV) 70.0 degrees TTL 2.650 mmf-number 4.50 EFL/R1 −0.71 |EFL/f1| 0.81 (R3 + R4)/(R3 − R4) 0.76

In the longitudinal spherical aberration diagram 4A of the secondembodiment, imaging point deviations of off-axis rays at differentheights are controlled to be within a range of ±0.025 mm. In the twofield curvature aberration diagrams of FIG. 4B and FIG. 4C, focal lengthvariations of three representative wavelengths in the whole field ofview falls within a range of ±0.025 mm. The distortion aberrationdiagram of FIG. 4D shows that the distortion aberration in the secondembodiment is kept within a range of ±40%. Thus, it can be seen that thewide-angle imaging lens 10 according to the second embodiment may beendowed with high optical imaging quality under the condition that theTTL has been reduced to approximately 2.650 mm.

FIG. 5 is a schematic diagram of a wide-angle imaging lens according toa third embodiment of the present invention. FIG. 6A to FIG. 6D arediagrams of a longitudinal spherical aberration and each aberrationaccording to the third embodiment. Referring to FIG. 5 at first, thethird embodiment of the wide-angle imaging lens 10 of the presentinvention is substantially similar to the first embodiment, and thedifference therebetween is as follows: each optical data, asphericalcoefficient and parameter between these lens elements 1, 2, 3, 4 and 5are more or less different. In addition, the image-side surface 42 ofthe fourth lens element 4 is a concave surface, and includes a concaveportion 422 located in the vicinity of the optical axis I and a concaveportion 424 located in the vicinity of a periphery. The object-sidesurface 51 of the fifth lens element 5 is a convex surface, and includesa convex portion 511 located in the vicinity of the optical axis I and aconvex portion 513 located in the vicinity of a periphery. It should benoted that, for clearly presenting the diagram, it should be mentionedthat the same reference numbers of the concave portions and the convexportions in the two embodiments are omitted in FIG. 5.

The other detailed optical data in the second embodiment is shown inTable 7. Each aspherical coefficient of the object-side surface 11 ofthe first lens element 1 to the image-side surface 52 of the fifth lenselement 5 in the third embodiment in Formula (1) is shown in Table 8.

TABLE 7 Third embodiment Curvature Name of the radius Spacing RefractiveAbbe Focal length element Surface (mm) (mm) index number (mm) ObjectInfinite Infinite First lens Object-side −0.699 0.220 1.545 55.9 −0.4759element 1 surface 11 Image-side 0.458 0.165 surface 12 Second lensObject-side 33.158 0.440 1.651 21.5 2.5159 element 2 surface 21Image-side −1.714 0.050 surface 22 Aperture 0 Infinite 0.050 Third lensObject-side 0.435 0.306 1.545 55.9 0.4985 element 3 surface 31Image-side −0.544 0.050 surface 32 Fourth lens Object-side −0.852 0.2201.651 21.5 −0.6371 element 4 surface 41 Image-side 0.890 0.050 surface42 Fifth lens Object-side 4.720 0.287 1.545 55.9 1.0087 element 5surface 51 Image-side −0.609 0.146 surface 52 Filter 9 Object-sideInfinite 0.150 1.516 64.1 surface 91 Image-side Infinite 0.350 surface92 Image plane Infinite 100

TABLE 8 Surface K A₄ A₆ A₈ 11 −2.4926E+01  1.0600E+00 −3.9206E+00 4.2914E+00 12 −7.0793E+00  1.7890E+01 −2.1040E+02  4.4030E+03 21−2.4769E+01 −2.1266E+00  9.4321E+01 −2.0433E+03 22 −9.9000E+01−3.2360E+00 −4.8262E+01  7.2036E+03 31  1.8031E+00 −4.5529E+00−4.0490E+00 −3.4634E+03 32 −2.3016E+01 −3.5130E+01  1.0050E+03−2.7008E+04 41  3.0715E+00 −3.2676E+01  6.4060E+02 −1.1517E+04 42−5.3079E+01 −4.7811E+00 −9.0150E+00  1.2669E+03 51  3.1449E+01 4.8277E+00 −1.8937E+02  2.7085E+03 52 −8.8901E+00  2.1751E+00 1.2258E−01 −3.3814E+02 Surface A₁₀ A₁₂ A₁₄ A₁₆ 11 0.0000E+00 0.0000E+000.0000E+00 0.0000E+00 12 −3.6871E+04  0.0000E+00 0.0000E+00 0.0000E+0021 2.1433E+04 −1.3799E+05  0.0000E+00 0.0000E+00 22 −2.9754E+05 4.7360E+06 0.0000E+00 0.0000E+00 31 1.2342E+05 −2.6092E+06  0.0000E+000.0000E+00 32 3.8948E+05 −2.5128E+06  0.0000E+00 0.0000E+00 411.9665E+04 7.4688E+05 0.0000E+00 0.0000E+00 42 −1.3838E+04  5.7943E+040.0000E+00 0.0000E+00 51 −1.7758E+04  5.5526E+04 −5.5948E+04  0.0000E+0052 3.9629E+03 −1.8524E+04  3.3060E+04 0.0000E+00

A relationship among important parameters in the wide-angle imaging lens10 according to the third embodiment is shown in Table 9.

TABLE 9 EFL 0.47 mm Half Angle of View (HFOV) 70.0 degrees TTL 2.483 mmf-number 4.40 EFL/R1 −0.67 |EFL/f1| 0.99 (R3 + R4)/(R3 − R4) 0.90

In the longitudinal spherical aberration diagram of the third embodimentshown in FIG. 6A, imaging point deviations of off-axis rays at differentheights are controlled to be within a range of ±0.01 mm. In the twofield curvature aberration diagrams of FIG. 6B and FIG. 6C, focal lengthvariations of three representative wavelengths in the whole field ofview falls within a range of ±0.01 mm. The distortion aberration diagramof FIG. 6D shows that the distortion aberration in the second embodimentis kept within a range of ±50%. Thus, it can be seen that the wide-angleimaging lens 10 according to the third embodiment may be endowed withhigh optical imaging quality under the condition that the TTL has beenreduced to approximately 2.483 mm.

FIG. 7 is a schematic diagram of a wide-angle imaging lens according toa fourth embodiment of the present invention. FIG. 8A to FIG. 8D arediagrams of a longitudinal spherical aberration and each aberrationaccording to the fourth embodiment. Referring to FIG. 7 at first, thefourth embodiment of the wide-angle imaging lens 10 of the presentinvention is substantially similar to the first embodiment, and thedifference therebetween is as follows: each optical data, asphericalcoefficient and parameter between these lens elements 1, 2, 3, 4 and 5are more or less different. In addition, the image-side surface 22 ofthe second lens element 2 is a concave surface, and includes a concaveportion 222 located in the vicinity of the optical axis I and a concaveportion 224 located in the vicinity of a periphery. The object-sidesurface 51 of the fifth lens element 5 is a concave surface, andincludes a concave portion 512 located in the vicinity of the opticalaxis I and a concave portion 514 located in the vicinity of a periphery.It should be noted that, for clearly presenting the diagram, it shouldbe mentioned that the same reference numbers of the concave portions andthe convex portions in the two embodiments are omitted in FIG. 7.

The other detailed optical data in the fourth embodiment is shown inTable 10. Each aspherical coefficient of the object-side surface 11 ofthe first lens element 1 to the image-side surface 52 of the fifth lenselement 5 in the fourth embodiment in Formula (1) is shown in Table 11.

TABLE 10 Fourth embodiment Curvature Name of the radius SpacingRefractive Abbe Focal length element Surface (mm) (mm) index number (mm)Object Infinite Infinite First lens Object-side −0.996 0.200 1.545 55.9−0.3645 element 1 surface 11 Image-side 0.266 0.157 surface 12 Secondlens Object-side 0.663 0.440 1.651 21.5 1.5973 element 2 surface 21Image-side 1.353 0.056 surface 22 Aperture 0 Infinite 0.010 The thirdlens Object-side 0.423 0.275 1.545 55.9 0.3901 element 3 surface 31Image-side −0.329 0.050 surface 32 Fourth lens Object-side −0.547 0.2001.651 21.5 −0.7905 element 4 surface 41 Image-side 9.795 0.050 surface42 Fifth lens Object-side −3.708 0.258 1.545 55.9 1.1674 element 5surface 51 Image-side −0.556 0.102 surface 52 Filter 9 Object-sideInfinite 0.150 1.56 64.1 surface 91 Image-side Infinite 0.350 surface 92Image plane Infinite 100

TABLE 11 Surface K A₄ A₆ A₈ 11 −9.9000E+01  4.3004E−01 −2.0093E+001.1862E+00 12 −1.1672E+00 −2.5559E+00  9.7652E+01 8.9671E+01 21−3.2680E+01  4.6320E+00 −1.5628E+01 −2.0898E+02  22  4.0674E+01 3.2007E−01 −1.6251E+02 3.5683E+04 31  3.2996E+00 −5.0175E+00 8.1882E+01 −7.7727E+03  32 −9.7119E+00 −2.1234E+01  8.4775E+02−2.2295E+04  41 −1.6901E+01 −1.2895E+01  5.1420E+02 −1.9108E+04  42−9.9000E+01 −2.8205E+00 −9.9542E+01 4.4210E+03 51  8.5999E+01 1.3451E+01 −6.3835E+02 1.4257E+04 52  7.7560E−01  1.5730E+01−1.8597E+02 1.2508E+03 Surface A₁₀ A₁₂ A₁₄ A₁₆ 11  0.0000E+00 0.0000E+000.0000E+00 0.0000E+00 12 −8.3965E+03 0.0000E+00 0.0000E+00 0.0000E+00 21 5.7819E+03 −5.3084E+04  0.0000E+00 0.0000E+00 22 −2.5561E+06 7.0932E+070.0000E+00 0.0000E+00 31  2.8162E+05 0.0000E+00 0.0000E+00 0.0000E+00 32 3.6267E+05 0.0000E+00 0.0000E+00 0.0000E+00 41  3.3218E+05 −1.5510E+06 0.0000E+00 0.0000E+00 42 −6.1367E+04 2.6939E+05 0.0000E+00 0.0000E+00 51−1.6621E+05 1.0103E+06 −2.8394E+06  0.0000E+00 52 −8.3141E+01−3.7712E+04  1.2816E+05 0.0000E+00

A relationship among important parameters in the wide-angle imaging lens10 according to the fourth embodiment is shown in Table 12.

TABLE 12 EFL 0.41 mm Half Angle of View (HFOV) 70.0 degrees TTL 2.298 mmf-number 4.40 EFL/R1 −0.41 |EFL/f1| 1.13 (R3 + R4)/(R3 − R4) −2.92

In the longitudinal spherical aberration diagram of the fourthembodiment shown in FIG. 8A, imaging point deviations of off-axis raysat different heights are controlled to be within a range of ±0.025 mm.In the two field curvature aberration diagrams of FIG. 8B and FIG. 8C,focal length variations of three representative wavelengths in the wholefield of view falls within a range of ±0.04 mm. The distortionaberration diagram of FIG. 8D shows that the distortion aberration inthe second embodiment is kept within a range of ±45%. Thus, it can beseen that the wide-angle imaging lens 10 according to the fourthembodiment may be endowed with high optical imaging quality under thecondition that the TTL has been reduced to approximately 2.650 mm.

In the embodiment of the present invention, the wide-angle imaging lens10 can achieve the following effects and:

A first lens element 1 for example, it is used to collect light, and thecurvature of the first lens element 1 is designed to be negative forlight that is used to receive a large angle.

The refractive index of the second lens element 2 is greater than therefractive index of the other lenses with refractive power (that is, thefirst lens element 1, the third lens element 3, the fourth lens element4 and the fifth lens element 5), and the Abbe number of the second lenselement 2 is less than the refractive index of the other lens elementswith refractive power, which can effectively correct the chromaticaberration.

The third lens element 3 focuses the imaged imaging beam and combines itwith the fourth lens element 4 having negative refracting power and thefifth lens element 5 having positive refracting power to effectivelycorrect spherical aberration, chromatic aberration and curvature offield.

In addition, in view of unpredictability of optical system design, theoptical imaging lens consistent with at least one of the followingconditional expressions under the architecture of the present inventionmay improve the imaging quality of the system better and therebyimproving the shortcomings of the prior art.

In the embodiments above, the wide-angle imaging lens 10 satisfies thefollowing conditions: −0.8≤EFL/R1<0. Since the first lens element 1compared to other lens elements with refractive power (i.e., the secondlens element 2, the third lens element 3, the fourth lens element 4 andthe fifth lens element 5) requires a large aggrieved fold, in thisrange, the object-side surface 11 of the first lens element 1 can reducethe ratio of the outer edge of the optical effective part of the E_(f1)to the outer edge of the optical invalid part of the E_(i) relative toits centre thickness, and can effectively reduce the size of the angleθ. Where, the centre thickness of the first lens element 1 refers to thedistance from the object-side surface 11 to the image-side surface 12 ofthe first lens element 1 on the optical axis I. The reference plane RP1is a plane passing through the outer edge Eft of the optical effectiveportion of the image-side surface 12, and the reference plane RP2 is anextended surface of the optical ineffective portion P_(n) close to theimage-side surface 12. The angle θ refers to the angle between thereference plane RP1 and the reference plane RP2.

In the above embodiments, the wide-angle imaging lens 10 satisfies thefollowing conditions: 0.8≤|EFL/f1|≤1.2, |EFL/f1| is the absolute valueof EFL/f1. If |EFL/f1| below the lower limit of 0.8, it will derive fromthe problem of insufficient light capacity for large angles, and if when|EFL/f1| is above the upper limit of 1.2, the effect of the first lenselement 1 on the light flexural force of the whole wide-angle imaginglens 10 becomes larger, which leads to the problem of tolerancesensitivity. If |EFL/f1| is within the aforementioned range, thewide-angle imaging lens 10 can avoid the above problems.

In the above embodiments, the wide-angle imaging lens 10 satisfies thefollowing conditions: −3.0≤(R3+R4)/(R3−R4)≤0.8. In this range, themanufacturing tolerances of the second lens element 2 are lesssensitive.

In the above embodiments, the angle of view of the wide-angle imaginglens 10 falls within a range of 130 to 150 degrees, and it has theadvantage of a wide-angle of view.

Based on the above, the wide-angle imaging lens of the embodiments ofthe present invention has the following beneficial effects: by concaveand convex shape design and arrangement of the object-side surfaces orimage-side surfaces of the lens elements and combination of therefractive power of the lens elements, the advantages of a narrow fieldangle effect, a relatively small TTL, and high imaging quality of thewide-angle imaging lens may be achieved.

The present invention has been disclosed as above with the embodimentsbut is not limited thereto. Those of ordinary knowledge in the art maymake certain modifications and embellishments without departing from thespirit and scope of the present invention. Therefore, the scope ofprotection of the present invention should be defined by the appendedclaims.

What is claimed is:
 1. A wide angle imaging lens, sequentiallycomprising a first lens element, a second lens element, an aperture, athird lens element, a fourth lens element and a fifth lens element froman object side to an image side along an optical axis, wherein each ofthe first lens element to the fifth lens element comprises anobject-side surface facing the object side and allowing imaging rays topass through and an image-side surface facing the image side andallowing imaging rays to pass through, and the lens elements withrefractive power are only the five lens elements; the first lens elementhaving negative refractive power, and the object-side surface of thefirst lens element being a concave surface in the vicinity of theoptical axis, and the image-side surface of the first lens element beinga concave surface; the second lens element having positive refractivepower, and the object-side surface of the second lens element being aconvex surface; the third lens element having positive refractive power,the object-side surface of the third lens element being a convexsurface, and the image-side surface of the third lens element being aconvex surface; the fourth lens element having negative refractivepower, the object-side surface of the fourth lens element being aconcave surface, and the image-side surface of the fourth lens elementcomprising a concave portion in the vicinity of the optical axis; andthe fifth lens element having positive refractive power, and theimage-side surface of the fifth lens element being a convex surface;wherein a field angle of the wide-angle imaging lens ranges from 130degrees to 150 degrees.
 2. The wide-angle imaging lens according toclaim 1, wherein the wide-angle imaging lens satisfies: −0.8≤EFL/R1<0,wherein EFL is the effective focal length of the wide-angle imaginglens, and R1 is the curvature radius of the object-side surface of thefirst lens element.
 3. The wide-angle imaging lens according to claim 1,wherein the wide-angle imaging lens satisfies: 0.8≤|EFL/f1|≤1.2, whereinEFL is an effective focal length of the wide-angle imaging lens, f1 is afocal length of the first lens element, and |EFL/f1| is an absolutevalue of EFL/f1.
 4. The wide-angle imaging lens according to claim 1,wherein the wide-angle imaging lens satisfies: −3.0≤(R3+R4)/(R3−R4)≤0.9,wherein R3 is a curvature radius of the object-side surface of thesecond lens element, and R4 is a curvature radius of the image-sidesurface of the second lens element.
 5. The wide-angle imaging lensaccording to claim 1, wherein the first lens element, the second lenselement, the third lens element, the fourth lens element and the fifthlens element have refractive power, the refractive index of the secondlens element is greater than or equal to the refractive index of theother lens elements with refractive power, and the Abbe number of thesecond lens element is less than or equal to the Abbe number of otherlens elements with refractive power.
 6. The wide-angle imaging lensaccording to claim 1, wherein the object-side surface of the first lenselement is a concave surface, and comprises a concave portion located inthe vicinity of a periphery, the object-side surface of the second lenselement is a convex surface, the image-side surface of the fourth lenselement comprises a concave portion located in the vicinity of theoptical axis and a convex portion located in the vicinity of aperiphery, the object-side surface of the fifth lens element comprises aconvex portion located in the vicinity of the optical axis and a concaveportion located in the vicinity of a periphery.
 7. The wide-angleimaging lens according to claim 1, wherein the object-surface of thefirst lens element comprises a convex portion located in the vicinity ofa periphery, the object-side surface of the second lens element is aconvex surface, the image-side surface of the fourth lens elementcomprises a concave portion located in the vicinity of the optical axisand a convex portion located in the vicinity of a periphery, theobject-side surface of the fifth lens element comprises a convex portionlocated in the vicinity of the optical axis and a concave portionlocated in the vicinity of a periphery.
 8. The wide-angle imaging lensaccording to claim 1, wherein the object-side surface of the first lenselement is a concave surface, and comprises a concave portion located inthe vicinity of a periphery, the object-side surface of the second lenselement is a convex surface, the image-side surface of the fourth lenselement is a concave surface, and comprises a concave portion located inthe vicinity of a periphery, the object-side surface of the fifth lenselement is a convex surface.
 9. The wide-angle imaging lens according toclaim 1, wherein the object-side surface of the first lens element is aconcave surface, and comprises a concave portion located in the vicinityof a periphery, the image-side surface of the second lens element is aconcave surface, the image-side surface of the fourth lens elementcomprises a concave portion located in the vicinity of the optical axisand a convex portion located in the vicinity of a periphery, theobject-side surface of the fifth lens element is concave surface.